companies say they use to show you better ads. but downy says they can sell the information to employers.. >> there are other uses of the data behind the scenes consumers don't know about or don't like. >> there is another consequence. researchers say tracking data accounts for a quarter of the internet use saying that is slowing down your computer, if you're on a mobile device, it can cost you money. >> there is band width you're wasting to power this tracking. >> that.am could lead to overyaz on wireless plan. downey says unless there is a law against it, it will only get worse. >> weather tonight? >> indeed. etc. cooled down. >> it has. we haven't had much time to adjust to this rather sudden change of the warmth. quite a chill right now. here is a live view from our sky 7 hd. traffic backed up in livermore, traffic, weather together. we've got cloudy skies with breaks in clouds. there are still areas that are receiving shower activity but for the most part you can see this is quieted down over the north bay throughout san fran